.App {
    width: 100px;
    height: 100px;
    background: orange;
}

.header {
    display: flex;
    text-align: center;
    line-height: 40px;
}

.header span {
    flex: 1;
    background: #544f6b;
    color: #8478B3;
}

.active {
    background: #fff !important;
    color: #8478B3 !important;
}

#main {
    width: 600px;
    height: 400px;
}